1. Technical Field
The present disclosure relates to a light emitting diode.
2. Discussion of Related Art
Semiconductor structures fabricated by gallium nitride for light sources, such as blue, green, and white light sources, have long lifetime, high energy conversion efficiency, and green. Therefore, the semiconductor structures are widely used as the light sources in large screen color display systems, automotive lightening, traffic lights, multimedia displays, optical communication systems, and so on.
A standard light emitting diode (LED) includes an N-type semiconductor layer, a P-type semiconductor layer, an active layer located between the N-type semiconductor layer and the P-type semiconductor layer, a first electrode electrically connected to the N-type semiconductor layer, and a second electrode electrically connected to the P-type semiconductor layer. In an operation, a positive voltage and a negative voltage are applied respectively to the P-type semiconductor layer and the N-type semiconductor layer. Thus, holes in the P-type semiconductor layer and electrons in the N-type semiconductor layer can enter the active layer and combine with each other to emit visible light, and the visible light is emitted from the semiconductor structure. The second electrode should be a transparent material, and is commonly made of indium tin oxide (ITO). However, the ITO has poor mechanical durability, low chemical endurance, and uneven resistance over an entire area. Thus, the LED has a relatively low efficiency and unstable property.
What is needed, therefore, is to provide an LED for solving the problem discussed above.